This invention relates to a method and apparatus for heating and cooling (climate control) of buildings and houses, where a typically 5-15 day thermal storage is integrated with heat-pumps and ventilation to operate in a particularly optimised synergy.
Large geographical areas in the world has a climate that generally goes through a seasonal change from a warm period in the summer to a cold period in the winter. This seasonal variation is naturally greatly dependent the local topography, whether there is an inland or coastal climate and the actual global latitude in question, but will nevertheless usually be of such an extent that buildings/houses needs means for cooling during the warm season and heating during the cold season in order to keep a comfortable indoor temperature of 20-22xc2x0 C. For example, in Norway the mean temperatures may vary from xe2x88x925xc2x0 C. to +20xc2x0 C. over a year, while Mediterranean countries and large parts of USA may typically see mean temperature changes from 0xc2x0 C. in winter to +30xc2x0 C. in summer. Thus, regardless whether one has a cold or warm climate, a substantial amount of energy is needed to keep a comfortable temperature in buildings/houses.
For Norway, which has a relatively cold climate and practically no use of air-conditioning, there is estimated that 71% of the energy consumption in living houses is spent on heating and producing hot water. This figure is somewhat lower for commercial buildings due to a larger demand for electric energy to operate technical machinery. The total energy consumption for heating houses and commercial buildings is estimated to 42.5 TWh/year. Pro capita this amounts to about 10 MWh/year for heating purposes, where approximately ⅔ is hydroelectric power. Despite that there is huge variations in energy consumption patterns in different regions in the world, it is nevertheless obvious from these figures that vast amounts of energy is spent in the world on heating/cooling of houses and buildings, and that there is a huge potential for energy conservation in this sector.
It is known that heat-pumps are very efficient tools for extracting heat energy from a low-temperature source and deposit the heat in a relatively high-temperature area. In general terms one might say that a heat-pump works like an inverted refrigerator, and can normally deliver 3-4 times more heat than their required energy input for driving the process. That is, while direct heating systems like gas fired heaters, wood firing, electric heating etc. has a theoretical upper limit of 100% efficiency and a practical efficiency well below this limit, conventionally available heat-pumps normally have efficiency rates which is in the order of 300-400%. Thus by using industrially available heat-pumps, the reduction in the energy consumption for heating/cooling of buildings can therefore for be as much as 70-80%.
There are known several types of heat-pumps, which generally can be characterised according to which medium they collect from and deliver the extracted heat to. For buildings and houses the heat will normally be delivered to a medium that is able to distribute the heat in the building, which in practice means water or air that is subsequently circulated in the building. For the heat source of heat-pumps there is a general convention stating that the heat source should have as high a temperature as possible and preferably be relatively stable over the year. This has led to use of heat sources such as a fluid medium circulated in deep drilled holes in bedrock, in buried tubes in the soil, in tubes submerged in fresh water, rivers, sea-water etc.
However, there are a number of problems associated with this approach. Rock and soil have a very low thermal conduction, thus the rock/soil needs a substantial amount of time to replace the heat extracted by the fluid medium. Thus one must employ rather lengthy loops and/or drilled holes in order to obtain a sufficiently large thermal store to allow long term extractions of heat without extensive cooling of the heat source. And as a consequence the investment cost often becomes prohibitive for this type heat extraction. The problem with low extraction capacity of the thermal stores can be solved by using open water as the heat source. It is possible to extract large amounts of heat from water at relatively small volumes (short extraction loops) due to a high specific heat capacity of water and the opportunity to replace extracted heat by convection. Also, water will at moderate depths have a stable and beneficially high temperature of 4xc2x0 C. Thus water is in many respects an ideal heat source. However, there are problems with corrosion and fouling, especially in sea-water, and this solution is strictly restricted to buildings and houses in the vicinity (within 100 m) of open water. The major part of buildings and houses lies outside this reach.
Another approach to reduce the high investment costs for heat-pumps is to extract heat from open air and transfer this heat to water or air that is distributed inside the buildings/houses. These heat-pumps may be installed directly it the walls of existing houses and give a point delivery of heat in the form of hot air. Such solutions are very competitively priced, but has a major drawback in that they significantly looses effect when the demand for heat is largest. That is, they loose much of their beneficial heat extraction effect when the open air temperature becomes low (below 0xc2x0 C.). Also, such solutions have encountered severe problems with freezing up of heat exchanger surfaces when the open-air temperature has fallen below +2xc2x0 C. Thus this solution is generally considered to be only suited for coastal climates where the temperature seldom falls below 0xc2x0 C.
Another approach for reducing the energy consumption for heating or cooling of buildings is to employ the natural seasonal temperature variations to build up sufficiently large thermal stores which is to be used in the following season to heat or cool the building. An example of such technology is SE 425 576. For instance, the heat resulting from solar radiation can be used advantageously for the heating of buildings and can eliminate the need for energy consuming heating systems. This form of passive solar heat gain is achieved through the architecture of the building by designing the building for optimising the absorption of solar rays over daily and annual cycles. That is, heat is accumulated by allowing the incident solar rays to fall onto a large thermal mass (generally walls or soil in the inside of the building), or is concentrated by various forms of heat collectors, and similarly accumulated. Greater or lesser heating is achieved by varying the amount of shade from the sunlight. The accumulation of heat allows it to be stored and used later when necessary. However, for cold climates the available solar radiation is less than for warmer climates while the need for heat is larger. As a consequence, the thermal stores must be very large in order to contain sufficient heat for a long and cold winter and also require extensive thermal insulation in order to preserve the heat over long periods (several months). Thus this solution is also encumbered with prohibitive costs, and have therefore not found general use.
The main objective of this invention is to provide a method and apparatus for heating and cooling of buildings and houses that solves the above given problems.
It is further an objective of this invention to provide